Infrared focal plane detector arrays can be mounted inside vacuum housings which allow the air to be evacuated and the detector array cooled down for testing. Making focus adjustments of the focal plane array (FPA) during testing requires either moving the entire vacuum housing or moving the detector inside the housing. Adjusting the focus or position of an entire vacuum housing or dewar containing the FPA can require movement of the vacuum port interface, external cables, etc., which often is not a feasible option. In cases where the vacuum housing cannot be moved, adjustment of the FPA while the vacuum housing is sealed and the FPA is cooled is difficult and time consuming. Many iterations of optical alignment adjustment while the sensor is being held under a vacuum may be required at great expense in cost and schedule. Sensor alignment can require multiple iterations in which the initial alignment is made, the sensor placed under vacuum, alignment shift assessed, the vacuum removed, calculated bias to the alignment is applied, the vacuum reapplied, and alignment rechecked under vacuum. Another approach has been to use vacuum feedthrough tools to adjust cold push-pull screws supporting the FPA, but this results in a momentary thermal short to the FPA requiring some time to thermally re-stabilize, and some vacuum loss as the feedthrough tools are being operated. Linear motion vacuum feedthrough micrometers can provide linear or rotational motion, but not tilting adjustment.
Reference will now be made to the examples illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.